Mushrooms With Sour Cream From Poland

MAKING
1) Heat butter and sauté onion in it over low heat until golden.
2) Blend milk with flour.
3) Pour the flour mixture to the sautéed onion and simmer.
4) Stir in mushrooms and half the sour cream and cook until mushrooms are soft.
5) Add seasonings and mix in rest of the sour cream.